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Question
Assertion :The sieve tube element contain P-protein. Reason: P-protein forms plug, when the sieve tube element is wounded.
Assertion :The sieve tube element contain P-protein. Reason: P-protein forms plug, when the sieve tube element is wounded.
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Solution
The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
P-proteins have been defined as proteinaceous material in the phloem, which is sufficiently characteristic when observed under electron microscope. Thus, this term mostly refers to structural proteins. There are other proteins also present within the phloem sap. Since they are soluble and not visible in the transmission of electron microscope, they do not strictly qualify as P-proteins. P-proteins have been divided into two major groups, non dispersive P-protein bodies and dispersive P-protein bodies. P-proteins are believed to play in “damage control” when phloem is damaged. Upon the disruption of a sieve element, the P-proteins quickly aggregate at the sieve plate to form a “clot” which prevents the leakage of phloem exudates through the wound. Thus, the correct answer is option B.
P-proteins have been defined as proteinaceous material in the phloem, which is sufficiently characteristic when observed under electron microscope. Thus, this term mostly refers to structural proteins. There are other proteins also present within the phloem sap. Since they are soluble and not visible in the transmission of electron microscope, they do not strictly qualify as P-proteins. P-proteins have been divided into two major groups, non dispersive P-protein bodies and dispersive P-protein bodies. P-proteins are believed to play in “damage control” when phloem is damaged. Upon the disruption of a sieve element, the P-proteins quickly aggregate at the sieve plate to form a “clot” which prevents the leakage of phloem exudates through the wound.
Thus, the correct answer is option B.
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